No abstract

No abstract

A high efficiency, maximum power point tracking (MPPT) power management unit (PMU), with 3.6 quiescent power, aimed at a thermoelectric generator (TEG) array is presented. The proposed energy harvesting PMU is made up of a boost converter with a cascaded capacitor-less low drop-out (CL-LDO) voltage regulator. The segmented approach allows the PMU to match the TEG array's changing dynamic series resistance via the boost converter and simultaneously provide voltage regulation with adaptive, high switching noise rejection via the CL-LDO. The boost converter's switching frequency is tracked via a Sense-and-Control loop which modifies the CL-LDO's power supply rejection (PSR) characteristics to place a notch in the PSR transfer function around the average. Experimental results show an overall system efficiency better than 57% @ 1.6 V output voltage, PSR of 40 dB at , and a notch-tuning range of 15-65 kHz. The total active area is 0.93 in 0.5 CMOS.

No abstract

Microbial Fuel Cell (MFC) technology is a novel Energy Harvesting (EH) source that can transform organic substrates in wastewater into electricity through a bioelectrochemical process. However, its limited output power available per liter is in the range of a few milliwatts, which results very limited to be used by an Internet of Things (IoT) smart node that could require power in the order of hundreds of milliwatts when in full operation. One way to reach a usable power output is to connect several MFCs in series or parallel; nevertheless, the high output characteristic resistance of MFCs and differences in output voltage from multiple MFCs, dramatically worsens its power efficiency for both series and parallel arrangements. In this paper, a Power Management System (PMS) is proposed to allow maximum power harvesting from multiple MFCs while providing a regulated output voltage. To enable a more efficient and reliable power-harvesting process from multiple MFCs that considers the biochemical limitations of the bacteria to extend its lifetime, a power ranking and MFC health-protection algorithm using an interleaved EH operation was implemented in a PIC24F16KA102 microcontroller. A power extraction sub-block of the system includes an ultra-low-power BQ25505 step-up DC-DC converter, which integrates Maximum Power Point Tracking (MPPT) capabilities. The maximum efficiency measured of the PMS was ~50.7%. The energy harvesting technique presented in this work was tested to power an internet-enabled temperature-sensing smart node.